TURNING METHOD FOR A CNC-LATHE

Abstract

A turning method for a computerized numerical control lathe performs the steps of: providing a cutting tool including a coupling portion, an intermediate portion and a cutting portion, a longitudinal center axis of the coupling portion defining a tool rotational axis, the cutting portion including a top surface, a first nose portion, the first nose portion including a first cutting edge, a second cutting edge, and a convex nose cutting edge connecting the first and second cutting edges; providing and rotating a metal work piece around a work piece rotational axis, which is set perpendicular to the work piece rotational axis; making a first pass where the first cutting edge is active and the second cutting edge is inactive; making a second pass where the first cutting edge is inactive and the second cutting edge is active; and rotating the turning tool around the tool rotational axis.

Claims

1. A turning method for a computerized numerical control lathe, the method comprising the steps of: providing a cutting tool including a coupling portion, an intermediate portion and a cutting portion, the intermediate portion extending between the coupling portion and the cutting portion, a longitudinal center axis of the coupling portion defining a tool rotational axis, the intermediate portion extending along the longitudinal center axis, the cutting portion including a top surface, the top surface facing away from the coupling portion, the cutting portion including a first nose portion, the first nose portion having a first cutting edge, a second cutting edge, and a convex nose cutting edge connecting the first and second cutting edges; providing a metal work piece; rotating the metal work piece around a work piece rotational axis; setting the tool rotational axis perpendicular to or substantially perpendicular to the work piece rotational axis; making a first pass such that the first cutting edge is active and such that the second cutting edge is inactive, making a second pass such that the first cutting edge is inactive and such that the second cutting edge is active, where the second pass is directed longitudinally or radially opposite or substantially opposite to the first pass; and rotating the turning tool around the tool rotational axis during the first pass and/or during the second pass and/or after the first pass but prior to the second pass.

2. The method according to claim 1, further comprising the step of during the second pass machining at least a portion of a machined surface from the first pass.

3. The method according to claim 1, further comprising the steps of: during the first pass, rotating the cutting tool in a first direction around the tool rotational axis; and during the first second pass, rotating the cutting tool in a second direction around the tool rotational axis wherein said second direction is opposite to said first direction.

4. The method according to claim 1, further comprising the steps of: withdrawing the cutting tool from the metal work piece after the first pass; and rotating the cutting tool around the tool rotational axis prior to the second pass.

5. The method according to claim 1, comprising the further steps of repeating the first and second passes in order to progressively cut a predefined feature into the metal work piece.

6. The method according to claim 1, further comprising the step of setting the tool rotational axis such that a tangent line of the metal work piece at the point of contact with the convex nose cutting edge intersect or substantially intersect the coupling portion.

7. The method according to claim 1, wherein the cutting portion includes a second nose portion, wherein the first and second nose portions each form free ends of the cutting tool, and wherein in a top view the first and second nose portions form an angle of more than 90 relative to each other measured around the longitudinal center axis of the intermediate portion.

8. The method according to claim 1, wherein the coupling portion and the intermediate portion jointly form a tool body, the cutting portion being in the form of a first cutting insert, wherein a front end of the tool body is defined by a first insert seat for the first cutting insert, wherein the first cutting insert is detachably clamped in the first insert seat by clamping means, wherein the first cutting insert includes a bottom surface opposite the top surface, wherein a side surface connects the top and bottom surfaces, wherein a mid-plane extends mid-way between the top and bottom surfaces, and wherein the nose cutting edge in the top view is convexly curved having a radius of curvature of 0.15-1.3 mm.

9. The method according to claim 7, comprising the further steps of: withdrawing the cutting tool from the metal work piece; and rotating the cutting tool around the tool rotational axis such that the first nose portion is moved away from the metal work piece and such that the second nose portion is moved towards the metal work piece.

10. The method according to claim 1, wherein the convex nose cutting edge intersects or substantially intersects the tool rotational axis, the longitudinal center axis being parallel to and spaced apart from the tool rotational axis.

11. The method according to claim 7, wherein the first and second nose portions are arranged symmetrically in relation to the longitudinal center axis, the longitudinal center axis being co-linear with the tool rotational axis.

12. The method according to claim 8, wherein the cutting tool includes a second cutting insert clamped in a second insert seat, wherein the second insert seat is formed in the intermediate portion of the tool body, wherein the second insert seat is positioned longitudinally between and spaced apart from the first cutting insert and the coupling portion, wherein the method comprises the further steps of withdrawing the cutting tool from the metal work piece, and moving the cutting tool in a forward direction along the tool rotational axis.

13. The method according to claim 1, comprising the further step of setting a maximum chip thickness to be constant or substantially constant during the first pass and/or the second pass.

14. The method according to claim 1, wherein the direction of rotation of the metal work piece around the work piece rotational axis is the same during both the first and second passes.

15. The method according to claim 1, wherein the first and second pass are in opposite directions longitudinally.

16. A computer program having instructions, which when executed by a computer numerical control lathe causes the computer numerical control lathe to perform the method according to claim 1.

17. A computer readable medium having stored thereon a computer program according to claim 16.

18. A data stream which is representative of a computer program according to claim 16.

Description

DESCRIPTION OF THE DRAWINGS

[0168] The present invention will now be explained in more detail by a description of different embodiments of the invention and by reference to the accompanying drawings.

[0169] FIG. 1 is a perspective view of a tool body which is part of a first cutting tool.

[0170] FIG. 2 is a perspective view of the first cutting tool.

[0171] FIG. 3 is a perspective view of the insert seat of the tool body in FIG. 1.

[0172] FIG. 4 is a side view of the cutting tool in FIG. 2.

[0173] FIG. 5 is a further side view of the cutting tool in FIG. 2.

[0174] FIG. 6 is a side view of a second cutting tool.

[0175] FIG. 7 is a perspective view of the cutting tool in FIG. 6.

[0176] FIG. 8 is a top view of the cutting tool in FIG. 6.

[0177] FIG. 9 is a perspective view of a third cutting tool.

[0178] FIG. 10 is a side view of the cutting tool in FIG. 9.

[0179] FIG. 11 is a perspective view of the tool body in FIG. 9.

[0180] FIG. 12 is a perspective view of the insert seat of the tool body in FIG. 11.

[0181] FIG. 13 is a perspective view of the cutting insert in FIG. 9.

[0182] FIG. 14 is a side view of the cutting insert in FIG. 13.

[0183] FIG. 15 is a top view of the cutting insert in FIG. 13.

[0184] FIG. 16 is a further perspective view of the cutting insert in FIG. 13.

[0185] FIG. 17 is a side view of a fourth cutting tool.

[0186] FIG. 18 is a further side view of the cutting tool in FIG. 17.

[0187] FIG. 19 is a perspective view of the cutting tool in FIG. 17.

[0188] FIG. 20 is a top view of the cutting tool in FIG. 17.

[0189] FIG. 21 is a start of a first pass according to a first turning method embodiment using the cutting tool in FIG. 6.

[0190] FIG. 22 is an end of the first pass shown in FIG. 21.

[0191] FIG. 23 is a start of a second pass according to a first turning method embodiment using the cutting tool in FIG. 6.

[0192] FIG. 24 is an end of a second pass shown in FIG. 23.

[0193] FIG. 25 is an illustration of a first pass according to a second turning method embodiment using the cutting tool in FIG. 9.

[0194] FIG. 26 is an illustration of a second pass according to a turning method using the cutting tool in FIG. 9.

[0195] FIG. 27 is an illustration of multiple passes according to a third turning method embodiment.

[0196] FIG. 28 is a side view of a turning method using the cutting tool in FIG. 9.

[0197] FIG. 29 is a side view of a turning method using the cutting tool in FIG. 9.

[0198] FIG. 30 is a side view of a turning method in FIGS. 25 and 26.

[0199] FIG. 31 is a perspective view of the cutting tool and metal work piece shown in FIG. 28.

[0200] FIG. 32 is a side view of a fourth turning method embodiment using the cutting tool in FIG. 17.

[0201] FIG. 33 is a side view of a fourth turning method embodiment using the cutting tool in FIG. 17.

[0202] FIG. 34 is a side view of a fifth turning method embodiment using the cutting tool in FIG. 6.

[0203] All cutting tool and cutting insert figures have been drawn to scale.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0204] The invention will now be described more in detail, and examples of cutting tools which can be used to perform the method according to the invention are described. Four cutting tools, or four embodiments of cutting tools, first-fourth cutting tools, are explained in more detail. Such cutting tools have been found to be particularly suitable for performing the above described turning method.

[0205] Reference is made to FIGS. 1-5 which shows a first cutting tool 1 comprising a tool body 3 and a cutting insert 2. The tool body 3 is shown in FIG. 1 without the cutting insert 2. The cutting tool comprises an insert seat 6 which is shown in FIG. 3. The cutting tool 1 is a turning tool, comprising a coupling portion 4, an intermediate portion 5 and a cutting portion 2. The coupling portion 4 and the intermediate portion 5 are permanently connected and jointly form a tool body 3 made from steel. The cutting portion 2 is in the form of a first cutting insert 2 made from cemented carbide. The cutting tool 1 according to the first embodiment comprises only one cutting insert.

[0206] The coupling portion 4 is suitable to a rotatable machine interface (not shown). The coupling portion 4 comprise a substantially conical or tapered portion 39 and a ring shaped portion 40 in accordance to ISO 26623-1:2014.

[0207] A front end 20 or a forward end of the tool body 3 is defined by a first insert seat 6 for the first cutting insert 2. The first cutting insert 2 is detachably clamped in the first insert seat 6 by clamping means 14, said clamping means being in the form of a clamping screw 14.

[0208] The first cutting insert 2 comprises a bottom surface 8 opposite a top surface 7. A side surface 9 connects the top and bottom surfaces 7, 8.

[0209] As seen in FIG. 4, a mid-plane M1 extends mid-way between the top and bottom surfaces 7, 8.

[0210] The intermediate portion 5 extends between the coupling portion 4 and the cutting portion 2.

[0211] A longitudinal center axis of the coupling portion 4 defines a tool rotational axis R1.

[0212] The intermediate portion 5 extends along a longitudinal center axis A1 thereof.

[0213] For the cutting tool 1 according to the first embodiment, the longitudinal center axis A1 is co-linear or co-axial with the tool rotational axis R1, as seen in FIGS. 2, 4 and 5.

[0214] The mid-plane M1 is perpendicular to the longitudinal center axis A1 of the intermediate portion 5, and perpendicular to the rotational axis R1. The top surface 7 of the first cutting insert 2 is facing away from the coupling portion 4. The top surface 7 is non-planar, and comprises chip breaking means or chip breakers, in the form of protrusions.

[0215] The first cutting insert 2 comprises a first and a second nose portion 10, 10, which each form free ends of the cutting tool 1.

[0216] The first nose portion 10 comprising a first cutting edge 11, a second cutting edge 12, both straight in a top view, and a convex nose cutting edge 13 connecting the first and second cutting edges 11, 12. The convex nose cutting edge 13 is convex in a top view. The nose cutting edge 13 is in top view convexly curved having a radius of curvature of 0.15-1.3 mm. Although a top view of the cutting tool according to the first embodiment is not shown, a top view of the first cutting insert 2 according to the first embodiment is shown in FIG. 8 which show an identical cutting insert.

[0217] According to the first embodiment, the radius of curvature is 0.4 mm. The first and second cutting edges 11, 12 forms a nose angle which is 35.

[0218] In a top view, the first and second nose portions 10, 10 form an angle of 180 relative to each other measured around the longitudinal center axis A1 of the intermediate portion 5.

[0219] The first cutting insert 2 is 180 symmetric in top and bottom views. The first cutting insert is in a top view parallelogram-shaped.

[0220] As seen in FIG. 3, the first insert seat 6 comprises first insert seat rotational locking means comprising ridges 23-26, where two ridges 23, 26 are co-linear, and two ridges 24, 25 are parallel.

[0221] The first cutting insert 2 comprises first cutting insert rotational locking means in the form of grooves (not shown), formed in the bottom surface 8, co-operating with the first insert seat rotational locking means 23-26. The first cutting insert 2 comprises a hole for the clamping screw 14. Said hole 13 intersects the top and bottom surfaces 8, 9, and a centre axis thereof defines a first cutting insert center axis co-linear with the rotational axis R1 and the longitudinal center axis A1.

[0222] The cutting tool 1 comprising a coolant channel formed in the tool body 3 and extending between the coupling portion 4 and a nozzle 28. Said nozzle 28 is formed in the intermediate portion 5, and the coolant channel and the nozzle 28 are arranged to direct a coolant fluid towards the first and second nose portions 10, 10.

[0223] Reference is now made to FIGS. 9-16 showing a second cutting tool 1, comprising a cutting insert 2. The principal differences compared to the first cutting tool relates to the designs of the cutting insert 2 and the insert seat 6.

[0224] In a top view as seen in FIG. 15, a first extension line 21 co-linear with the first cutting edge 11 and a second extension line 22 co-linear with the second cutting edge 12 extends on opposite sides relative to the first cutting insert center axis A2, which axis is co-linear with the rotational axis R1 and the longitudinal center axis A1 when the cutting insert 2 is mounted in the insert seat 6. The previous sentence is true also for the cutting tool 1 according to the first embodiment.

[0225] The first cutting insert 2 comprises three nose portions 10, 10, 10. The first cutting insert 2 is 120 symmetrical in top and bottom views. In a top view as seen in FIG. 15 the first and second cutting edges 11, 12 forms a nose angle which is 35.

[0226] As seen in FIG. 12, the first insert seat 6 comprises first insert seat rotational locking means comprising ridges 23-25, where said ridges 23-25 extend radially in relation to a hole 32 for the clamping screw 14 formed in the first insert seat 6.

[0227] The first cutting insert 2 comprises first cutting insert rotational locking means comprising grooves 16-18 formed in the bottom surface 8, co-operating with the first insert seat rotational locking means 23-26.

[0228] Reference is now made to FIG. 17-20, showing a fourth cutting tool 1. The fourth cutting tool 1 principally differs from the first cutting tool in that the cutting tool 1 comprises a second and a third cutting insert 29, 30, clamped our mounted in a second and third insert seat, respectively. Said second and third insert seats are formed in the intermediate portion 5 of the tool body 3 longitudinally between and spaced apart from the first cutting insert 2 and the coupling portion 4.

[0229] The second cutting insert 29 and the third cutting insert 30 is each different in shape in a top view compared to the first cutting insert 2. The third cutting insert 30 is a threading insert.

[0230] The second and third cutting insert 29, 30 each comprises nose portions, where each of said nose portions comprises a set of cutting edges.

[0231] Compared to the first cutting insert 2, the second and third cutting inserts 29, 30 are placed at a greater distance from the longitudinal center axis A1 of the intermediate portion 5.

[0232] In a top view as seen in FIG. 20, the second and third cutting inserts 29, 30 forms equally large angles or substantially equally large angles in relation to the first and second nose portions. In FIG. 20, the first cutting insert comprise two nose portions 10, 10 which are placed at 6 o'clock and at 12 o'clock, respectively. The second cutting insert 29 is placed at 9 o'clock, and the third cutting insert 30 is placed at 9 o'clock, where the time references refers to an analogue 12-hour watch and relates to the relative position in relation to the longitudinal center axis A1. By such a cutting tool, the clearance is further improved.

[0233] As seen in FIG. 17, the second and third cutting inserts 29, 30 are positioned longitudinally at equal distances or substantially equal distances from the clamping portion 4.

[0234] Reference is now made to FIG. 6-8, showing a second cutting tool 1. The second cutting tool 1 principally differs from the first cutting tool in that for the second cutting tool 1, the longitudinal center axis A1 is parallel to and spaced apart from the tool rotational axis R1, and the convex nose cutting edge 13 of the first nose portion 10 intersects or substantially intersects the tool rotational axis R1. In other words, the intermediate portion 5 is offset in relation to the tool rotational axis R1. A mid-point of the convex nose cutting edge 13 of the first nose portion 10 is positioned less than or equal to 0.5 mm from the tool rotational axis R1.

[0235] In other respects, the second cutting tool 1 is similar to the first cutting tool. For example, in a top view as seen in FIG. 8 a first extension line 21 co-linear with the first cutting edge 11 and a second extension line 22 co-linear with the second cutting edge 12 extends on opposite sides relative to the longitudinal center axis A1 of the intermediate portion 5.

[0236] In accordance with the first, third and fourth embodiment, in a top view as seen in FIG. 8, the intermediate portion 5 and the first cutting insert 2 is inside an outer boundary line of the coupling portion 4.

[0237] Reference is now made to FIGS. 21-24 showing a turning method according to a first embodiment for a computerized numerical control lathe (not shown). The second cutting tool 1 is provided, although any of the above described cutting tools may be used. The cutting insert 2 comprises first and second nose portions 10, 10. In the method in FIGS. 21-24, the second nose portion 10 is in an active position. The method can alternatively be performed where the first nose portion 10 is in an active position. In such case, the cutting tool 1 is 180 rotated around the tool rotational axis R1.

[0238] A metal work piece 31 is provided, which rotates around a work piece rotational axis R2. The tool rotational axis R1 is perpendicular to the work piece rotational axis R2. In the example, the work piece rotational axis R2 is in a horizontal position and the tool rotational axis R1 is in a vertical position. One possible alternative is to arrange the work piece rotational axis R2 is in a vertical position and the tool rotational axis R1 in a horizontal position.

[0239] The method comprises the step of making a first pass 36 by moving the cutting tool 1, seen in top view, such that the first cutting edge 11 is active, such that the second cutting edge 12 is inactive, and such that a machined surface 38 is formed by the nose cutting edge 13. The start of the first pass 36 is shown in FIG. 21. The end or the finish of the first pass is shown in FIG. 22.

[0240] The method comprises the step of making a second pass 37 by moving the cutting tool 1 such that the first cutting edge 11 is inactive, such that the second cutting edge 12 is active, and such that at least a portion of a machined surface 38 from the first pass 36 is machined, where the second pass is longitudinally or radially opposite or substantially opposite to the first pass. The start of the second pass 37 is shown in FIG. 23. The end or the finish of the second pass is shown in FIG. 24. For the method shown in FIGS. 21-24, the second pass is longitudinally opposite to the first pass.

[0241] As can be seen from FIGS. 21 and 22, said first pass is linear. Thus, said first pass can be defined by a component 32 which is parallel to the work piece rotational axis R2, i.e. along the work piece rotational axis R2.

[0242] As can be seen from FIGS. 23 and 24, said second pass is linear. Thus, said second pass can be defined by a component 33 which is parallel to the work piece rotational axis R2 and opposite to the component 32 for the first direction.

[0243] As can be seen in FIGS. 21 and 22, the start and end position for the first pass 36 are spaced apart.

[0244] During the first and second passes 36, 37 an entering angle is constant.

[0245] The direction of rotation of the metal work piece 31 around the work piece rotational axis R2 is the same during both the first and second passes 36, 37.

[0246] After the first pass 36 but prior to the second pass 37, the cutting tool 1 is withdrawn from the metal work piece 31.

[0247] After the withdrawing of the cutting tool 1 but prior to the second pass 37, the cutting tool 1 is rotated around the tool rotational axis R1 by an angle which is in the range of 40-130.

[0248] Attention is now drawn to FIGS. 25-26, which show a turning method according to a second embodiment using the third cutting tool. Only the cutting insert 2 of the cutting tool is shown. The method can be used using any of the above described cutting tools.

[0249] A metal work piece 31 is provided, which rotates around a work piece rotational axis R2. The tool rotational axis (not shown) is perpendicular to the work piece rotational axis R2. The method comprises the step of making a first pass, shown in FIG. 25, by moving the cutting tool such that the first cutting edge 11 is active, such that the second cutting edge 12 is inactive, and such that a machined surface 38 is formed by the nose cutting edge 13. Five positions of the cutting insert 2 is shown, starting from the right-hand side and moving towards the left-hand side.

[0250] The method comprises the step of making a second pass, shown in FIG. 26, by moving the cutting tool such that the first cutting edge 11 is inactive, such that the second cutting edge 12 is active, and such that at least a portion of a machined surface 38 from the first pass is machined. During the first pass the cutting tool rotates in a first direction, counter-clockwise in FIG. 25, around the tool rotational axis.

[0251] During the second pass the cutting tool rotates in a second direction around the tool rotational axis, where said second direction, clock-wise in FIG. 26, is opposite to said first direction.

[0252] During the first pass as seen in FIG. 25, the cutting tool is moved along a non-linear or curved line. The first pass comprises a longitudinal component 32 which is towards the left-hand side.

[0253] During the second pass as seen in FIG. 26, the cutting tool is moved along a non-linear or curved line. The second pass comprises a longitudinal component 33 which is towards the right-hand side, i.e. opposite to the longitudinal component 32 of the first pass.

[0254] During the first and second passes, an entering angle is constant.

[0255] After the first pass but prior to the second pass, the cutting tool is withdrawn from the metal work piece 31.

[0256] The direction of rotation of the metal work piece 31 around the work piece rotational axis R2 is the same during both the first and second passes 36, 37.

[0257] Attention is now drawn to FIG. 27, which show a turning method according to a third embodiment. Any of the above described turning tools can be used. A first and second pass 36, 37 is shown. Said first and second passes 36, 37 are similar or substantially similar to the turning method according to the second embodiment. The first and second passes 36, 37 are repeated in order to progressively cut a predefined feature into the metal work piece. In other words, the turning method according to the third embodiment comprises a series of alternating passes of the cutting tool, where subsequent passes are in opposite or substantially opposite directions.

[0258] The direction of rotation of the metal work piece around the work piece rotational axis is the same during both the first and second passes 36, 37.

[0259] Attention is now drawn to FIG. 28, showing in a side view the relative position and orientation of a metal work piece 31 and the third cutting tool 1. Alternatively, any other of the above described cutting tools can be used. The cutting tool 1 comprises a coupling portion 4 clamped to a machine interface 40 of a CNC-lathe (not shown), an intermediate portion 5 and a cutting portion 2 in the form of a cutting insert. The CNC-lathe (not shown) can be instructed to perform the turning method by instructions in a computer program, a computer readable medium or a data stream. A longitudinal center axis of the coupling portion 4 defines a tool rotational axis R1. The intermediate portion 5 extends along a longitudinal center axis A1 thereof. The cutting portion 2 comprises a top surface facing away from the coupling portion 4.

[0260] The metal work piece 31 rotates around a work piece rotational axis R2 in a clock-wise direction in FIG. 28.

[0261] The tool rotational axis R1 is perpendicular to the work piece rotational axis R2. The tool rotational axis R1 is arranged such that a tangent line of the metal work piece 31 at the point of contact with the convex nose cutting edge 13 intersect the coupling portion 4. The tangential cutting force is directed towards the machine interface 40. The tool rotational axis R1 is spaced apart by a distance from a peripheral surface of the metal work piece 31. The tool rotational axis R1 is parallel to said tangent line.

[0262] Attention is now drawn to FIG. 29, showing the relative position and orientation of a metal work piece 31 and the third cutting tool 1. The arrangement in FIG. 29 differs from FIG. 28 only in that the tool rotational axis R1 is not parallel to said tangent line, but forms an angle less than or equal to 10 in relation to said tangent line.

[0263] Attention is now drawn to FIG. 30, showing a side view of the center position of the cutting insert 2 from FIGS. 25 and 26, including the cutting tool 1.

[0264] Attention is now drawn to FIG. 31, showing a perspective view of the arrangement shown in FIG. 28. The metal work piece 31 shown is cylindrical and comprises a lateral surface 31, i.e. a surface facing away from the work piece rotational axis R2, and a base surface 42, i.e. a surface facing in a direction parallel to the work piece rotational axis R2. The metal work piece 31 comprises a second base surface, facing away from the viewer. In the first, second, third and fourth turning methods describe above, machining is made in a lateral surface 41 of a metal work piece 31. In the fifth turning method described below, machining is made in a base surface 42 of a metal work piece 31.

[0265] Attention is now drawn to FIGS. 32 and 33, showing a turning method according to a fourth embodiment, using the fourth cutting tool 1.

[0266] The method includes any of the above described turning methods, using the first cutting insert 2, where the fourth cutting tool 1 is in a position relative to the metal work piece 31 as shown in FIG. 32. The method further comprises the steps of withdrawing the cutting tool 1 from the metal work piece 31, and moving the cutting tool 1 in a forward direction along the tool rotational axis R1 to the position shown in FIG. 33. The method further comprises the step of rotating the cutting tool 1 around the tool rotational axis R1 by a predetermined angle, such that the second cutting insert 29 is in an active position. Said predetermined angle is within the range of 80-100

[0267] Reference is now made to FIG. 34, showing a turning method according to a fifth embodiment using the second cutting tool 1, although any of the above described cutting tools may be used.

[0268] A metal work piece 31 is provided, which rotates around a work piece rotational axis R2. The tool rotational axis R1 is perpendicular to the work piece rotational axis R2.

[0269] Unlike the previous described turning methods, the machining during the turning method according to the fifth embodiment is made at a base surface of the metal work piece 31.

[0270] The tool rotational axis R1 is perpendicular to the work piece rotational axis R2. In the example, both the work piece rotational axis R2 and the tool rotational axis R1 is in a horizontal position. One possible alternative is to arrange both the work piece rotational axis R2 and the tool rotational axis R1 in a vertical position.

[0271] The cutting insert 2 comprises first and second nose portions 10, 10. In the method in FIG. 34, the second nose portion 10 is in an active position.

[0272] The method can alternatively be performed where the first nose portion 10 is in an active position. In such case, the cutting tool 1 is 180 rotated around the tool rotational axis R1.

[0273] The method comprises the step of making a first pass 36 by moving the cutting tool such that the first cutting edge 11 is active, such that the second cutting edge 12 is inactive, and such that a machined surface is formed by the nose cutting edge 13.

[0274] The method comprises the step of making a second pass 37 by moving the cutting tool such that the first cutting edge 11 is inactive, such that the second cutting edge 12 is active, and such that at least a portion of a machined surface from the first pass 37 is machined.

[0275] During the first pass the cutting tool rotates in a first direction, counter-clockwise in FIG. 34, around the tool rotational axis R1.

[0276] During the second pass 37 the cutting tool rotates in a second direction around the tool rotational axis, where said second direction, clock-wise in FIG. 34, is opposite to said first direction.

[0277] During the first pass 36 the cutting tool is moved along non-linear or curved path. The first pass comprises a radial component 34 which is perpendicular to and towards the work piece rotational axis R2, downwards in FIG. 34.

[0278] During the second pass 37 the cutting tool is moved along a path which is non-linear or curved. The second pass comprises a radial component 35 which is perpendicular to and away from the work piece rotational axis R2, upwards in FIG. 34, i.e. opposite to the radial component 34 of the first pass.

[0279] During the first and second passes, an entering angle is constant.

[0280] After the first pass 36 but prior to the second pass 37, the cutting tool is withdrawn from the metal work piece 31.

[0281] The direction of rotation of the metal work piece 31 around the work piece rotational axis R2 is the same during both the first and second passes 36, 37.

[0282] In the present application, the use of terms such as including is open-ended and is intended to have the same meaning as terms such as comprising and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as can or may is intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such. Terms such as upper, upwards, lower, top, bottom, forward, front and rear refer to features as shown in the current drawings and as perceived by the skilled person.